It's a neat design challenge to make a one-player mission into a two-player one - whether that style be using Archon Mode or a Co-Op one.
For instance, take Brood War's Episode 4 Mission 6, "Return to Char". The player is given one Protoss camp, and one Zerg camp, to complete the mission. Sounds like a straight-up Co-Op mission, to me. OR you could take the Archon way and in-game explain that Artanis and Kerrigan are both controlling his units AND her swarm. Hmm. No, that doesn't seem right. Co-Op it should be for that mission.
But take Brood War's Episode 6 Mission 5, "True Colors", into consideration - one army vs. two factions - and Archon Mode would work wonderfully there!
However, there are many missions that wouldn't really need an Archon or Co-Op Mode to make them enjoyable. Sometimes, like WoL's Ghost of a Chance, it wouldn't make sense.

Yes, Blizzard is against putting out official SP maps with modded content.
For a custom campaign, however...

Like I said, it's a neat design challenge for campaign makers out there.

So, changes in the past affect the present (future). Question number 1: do these "changes" apply only to in-mission changes, or to the campaign as a whole? Say I destroy an enemy faction completely in the past. Does that mean that the rest of the campaign in the future would be easier? or changed? Or will that only affect that mission specifically?

Question 2: will the two time periods be running concurrently? For instance, does the battle in the future continue while the player is in the past? If the player uses the time-travel mechanic to work on a micro-intensive stealth mission in the past, but must also be keeping tabs on an all-in push from a large army in the future, that'd be a source of frustration for some (and no problem for others). One way to handle this is to PAUSE or HALT the action in the other battlefield if the player uses the time travel mechanic.

In terms of real-world mechanics, consider that changing the past would change so many conditions in the future. For example, you have a mission in the future to destroy the enemy faction. One objective is to go to the past and do... something. You return to the future, and suddenly you are expected to remember that your objective is to SAVE the faction you thought was once the enemy, but is now your ally.
To the player, this just plain seems like a whiplash-inducing whirlwind of action, to say nothing about the design process required to get this to work.

I guess it comes down to, how much freedom do you want to give the player in changing the past?
Keep in mind the BRANCHING design prevalent in time-travel games: just as there are optional objectives in campaigns, there can also be optional objectives x 2 (for a total of 4 times the design work) for two time periods. If the past optional objective is met, then you have a new set of triggers for affecting the future. x 2 for the main objectives.

1 - Main objective met, optional met => Makes one version of the future...
2 - Main objective not met, optional met => Makes another version...
3 - Main objective met, optional not met => And another...
4 - Main objective not met, optional not met => And yet another.

Multiply the top list by two for every additional objective, Main or not, added to a mission in the past.

If you want to get some insight on how this works in another setting, I'd invite you to go watch the final two-part episode of Star Trek: The Next Generation, "All Good Things...". Basically Picard does JUST what you want to do, with 3 time periods.

... and not the tracks that you are thinking about! I'm looking specifically for the music of the cinematics from StarCraft1 & Brood War. Blizzard once released a couple of cinematic BGMs on the official StarCraft 1 Soundtrack that you can find on iTunes, but I'm certain that not all of them were there. Anybody else know how to rip / find the missing cinematic BGMs?

Could anyone - ANYONE - please make the models and actor data for the SC2-Alpha ground-based Corruptor? That'd be neat to have. Here's a picture of some Alpha units; the Corruptor is the unit underneath the Ultralisk, next to the Zergling and the Fatty (Infestor), or the unit to the north of the Hydralisks. Thnx!

The map is okay, despite a few issues and bugs to be found throughout. First and foremost, as an answer to what this map is: it's a melee-styled map where your team (maximum of 16 players?) starts out with a certain number of heroes with certain special abilities, a base, and a starting size of worker units. The tech-tree is almost the same, but you will quickly notice that there are newer structures, units, and upgrades, even though the icons don't look anything like what you'd be building and the tooltips don't help at all. (MAYBE that'd be something to fix, Sc2HeroMap.) But, for example, you get to build some campaign-exclusive units like Protoss Preservers and Terran Warhounds.

The main issue might be balancing of hero units, which basically will make or break your faction in the early to mid-game. Computer foes also have the tendency to be super-aggressive in most playthroughs, so you'd have to get the jump on them if you want to survive.

I'm sorry to announce that I have to pull out of the project. School just started up, and the schedule is going to cause problems for me for the next 4 months. I'll release everything I've completed, but the rest is up to you guys. I'll probably still post around here when I have time, but I can't actively work on the project for the next while. So sorry.

If we're looking to be as faithful to the SC1 engine as possible, then we need to completely screw up the pathing algorithms for each unit as well. *rolls eyes* Come on, guys! Let's be a bit smarter about this!

I'm with Soul on this issue. Roll back the footprints; SC1 players playing SC2 have had to change their tactics once before, so they can do it again.